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Topic: Thorium Fuel Engine (Read 9711 times)

yes there are other fissile isotopes like Neptunium and Californium, but they can't be made nearly as efficiently or cost effectively as U233, U235, or Pu239. Neptunium is produced in reactors about 20 times slower than Plutonium.

yes there are other fissile isotopes like Neptunium and Californium, but they can't be made nearly as efficiently or cost effectively as U233, U235, or Pu239. Neptunium is produced in reactors about 20 times slower than Plutonium.

But all neptunium in spent fuel from *power reactors* is still weapons-grade, unlike plutonium. US alone has 75000 tons of spent fuel. It contains, very roughly, 50 tons of Np.

-- many reactors during the Cold War produced both weapons-grade Pu and electric power for the commercial grid. In the 50s and 60s, the UK Central Electricity Generation Board produced more Pu than the modest British nuclear weapons program could use, so the surplus was bartered to the USA in return for tritium from Savannah River. The Soviet RBMK reactors were similar to the British ones and had the same dual purpose. They also had similar accidents (Windscale and Chernobyl). In the US some of the Hanford Pu production reactors also fed the grid, but this was on a much smaller scale.

-- It's not clear that the distinction between "reactor-grade" and "weapons-grade" Pu has any meaning anymore. The US apparently produced warhead designs using reactor-grade Pu around 1960, but the last time I checked they didn't admit having tested them. In the 1980s there was a short-lived program to produce "super-grade" Pu with very low Pu-240 content that could be mixed with reactor-grade Pu to produce a weapons-grade product. Most proliferation experts think that Japan's huge stockpile of "reactor-grade" Pu is intended as a weapons reserve -- they have never built the fleet of breeder reactors it is supposedly for.

-- there were two periods of interest in the Th-232/U-233 breeder cycle. In the 1950s there was hope in the USA that U-233 would be a useful material for weapons, but when its nuclear properties were measured it turned out to be pretty useless. India did some work on it in the 1970s because they have much larger domestic reserves of thorium than uranium (in some areas the natural background radiation from thorium actually exceeds that allowed in US nuclear plants). But nothing came of this program either.

Today's modest interest in thorium breeding seems mostly because it is different, and it is easy to mistake "different" for "better". You see this all the time on the other threads on this site, where old bad ideas about spaceflight are dug up and proclaimed as the best thing since sliced bread.

I think OP mixed two things. Molten salt reactors and Thorium reactors - those are often connected but are separate things. If that's a case - molten salt reactors are supposed to be much smaller and use coolant which doesn't have to be in super bulky extremely high pressures loop and under super heavy contamination dome. That's huge advantage - that's why original research on MSR was done by money from USAF - they hoped to put those reactors on planes.

As for space... I have no idea how standard nuclear reactors could be used. There is no river around to provide heat sink and classical solution - change heat to electric energy via steam turbine - seems to be in realm of fantasy. As for space as Mars, Moon... that could be a thing. I hope it will be.

As for space... I have no idea how standard nuclear reactors could be used. There is no river around to provide heat sink and classical solution - change heat to electric energy via steam turbine - seems to be in realm of fantasy.